Those rental car companies are responsible for buying and then selling a lot of cars that eventually make their way into the used car market. Now that they haven't been renting or buying as much that means not as many cars are flowing in that might be needed.
A computer chip shortage is also said to be contributing to the problem as well.
Many people who are financially struggling through the pandemic also aren't looking at new cars right now, they're looking for something that can save them money and something that they can afford.
Right now it's reported that the used car supply in a variety of places cannot keep up with the growing demand that they're seeing for used cars in the market.
This means good news for those who might be looking to trade theirs in, but for those looking for a sale you might be waiting awhile.